Sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 April 2017 - 02 June 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 439 (In Vitro Skin Irritation: Reconstructed Human Epidermis Test Method)

Version / remarks:

(Original Guideline adopted July 28, 2015)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium 4-[(octadecylamino)carbonyl]benzoate

EC Number:

227-822-4

EC Name:

Sodium 4-[(octadecylamino)carbonyl]benzoate

Cas Number:

5994-45-6

Molecular formula:

C26H43NO3.Na

IUPAC Name:

Sodium 4-[(octadecylamino)carbonyl]benzoate

Constituent 2

Reference substance name:

Sodium 4-[(hexadecylamino)carbonyl]benzoate

Molecular formula:

C24H39NO3.Na

IUPAC Name:

Sodium 4-[(hexadecylamino)carbonyl]benzoate

Test material form:

solid: bulk

Details on test material:

The substance was pre-registered under the identifier sodium 4-[(octadecylamino)carbonyl] benzoate (EC 227-822-4, CAS 5994-45-6) but was previously registered under the identifier Sodium 4-[(alkylamino)carbonyl]benzoate, C16-18, predominantly C18 and this was the name used in the study reports for the testing of this substance. After initial registration, following feedback from ECHA’s substance adaptation service, the new substance identity sodium 4-[(C16-18-(even numbered)-alkylamino)carbonyl]benzoate (EC 701-278-2) was assigned.

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Batch: A026/99 and A026/50-01
- Purity: 100% (UVCB)
- Appearance: White solid
- Expiration date: 01 July 2019

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Room temperature

In vitro test system

Test system:

other: EPISKIN™ Reconstructed Human Epidermis Model

Source species:

other: EPISKIN™ Reconstructed Human Epidermis Model

Cell type:

non-transformed keratinocytes

Cell source:

other: EPISKIN™ Reconstructed Human Epidermis Model

Source strain:

other: EPISKIN™ Reconstructed Human Epidermis Model

Details on animal used as source of test system:

Source: EpiSkin™ model kit.
Supplier: EpiSkin™ kits are purchased from SkinEthic Laboratories (69007 Lyon, France).
EpiSkin™ Kit Lot No.: 17-EKIN-022

Justification for test system used:

In an international validation study performed by ECVAM, the in vitro skin irritation test using the human skin models EpiSkin™ and EpiDerm™ and measurement of cell viability by dehydrogenase conversion of MTT into a blue formazan salt have turned out as a sufficiently promising predictor for skin irritancy potential.

Vehicle:

unchanged (no vehicle)

Details on test system:

RECONSTRUCTED HUMAN EPIDERMIS (RHE) TISSUE
- Model used: EPISKIN™ Reconstructed Human Epidermis Model Kit
- Tissue batch number(s): 17-EKIN-022
- Delivery date: 30 May 2017
- Date of initiation of testing: 30 May 2017

TEMPERATURE USED FOR TEST SYSTEM
- Temperature used during treatment / exposure: 37°C
- Temperature of post-treatment incubation (if applicable): 37°C

REMOVAL OF TEST MATERIAL AND CONTROLS
- Volume and number of washing steps: Rinsing was achieved by filling and emptying each tissue using a soft stream of PBS to gently remove any residual test item
- Observable damage in the tissue due to washing: Not specified
- Modifications to validated SOP: None

MTT DYE USED TO MEASURE TISSUE VIABILITY AFTER TREATMENT / EXPOSURE
- MTT concentration: 2 mL assay medium containing 0.3 mg/mL MTT per well
- Incubation time: 3 hours
- Spectrophotometer: Microplate reader (Versamax® Molecular Devices, 85737 Ismaning, Germany, version 4.7.1)
- Filter: 570 nm
- Filter bandwidth: Not applicable
- Linear OD range of spectrophotometer: Not specified

FUNCTIONAL MODEL CONDITIONS WITH REFERENCE TO HISTORICAL DATA
- The results for the positive control are within the historical data (means, rel. standard deviation, and ranges) of Envigo CRS GmbH
- The results for the negative control are within the historical data (means, rel. standard deviation and ranges) of Envigo CRS GmbH (Please note: the study was performed by using PBS, the Historical Control Data Base annexed to the report shows the Data for deionized water; data for PBS are in process and the number of studies is still too low for presenting Historical Data). Comparing the results of PBS to the Historical Control Data Base generated with deionized water is legitimate since both controls are aqueous from the chemical point of view. In other toxicological studies (e.g. OECD 487 or OECD 473) Historical Data Bases distinguish only between aqueous or organic solvents.

NUMBER OF REPLICATE TISSUES: 3

CONTROL TISSUES USED IN CASE OF MTT DIRECT INTERFERENCE
- Since the colour did not turn blue/purple, the test item was not considered to be a MTT reducer. Therefore, it was not necessary to perform an additional test with freeze-killed tissues to determine a correction factor for calculating the true viability in the main experiment.

NUMBER OF INDEPENDENT TEST SEQUENCES / EXPERIMENTS TO DERIVE FINAL PREDICTION: Three
- Test for Direct MTT Reduction
- Test for Direct Colour Interference
- Main test

PREDICTION MODEL / DECISION CRITERIA
- The test substance is considered to be an irritant to skin if the relative mean tissue viability after a 15 minute exposure period followed by the 42-Hour post-exposure incubation period is less than or equal to 50%.
- The test substance is considered to be non-corrosive to skin if the viability after 15-Minute exposure period followed by the 42-Hour post-exposure incubation period is greater than 50%.

Control samples:

yes, concurrent negative control

yes, concurrent positive control

Amount/concentration applied:

TEST MATERIAL
- Amount applied: 5 μL of deionised water followed by 10 ± 2 mg of the test item were topically applied to the epidermal surface
- Concentration (if solution): Test material is a solid

VEHICLE
- Not applicable

NEGATIVE CONTROL
- Name: PBS (produced in-house: 40 g NaCl, 1 g KCl, 1 g KH2PO4, 0.94 g Na2HPO4 + 2 H2O filled to 5000 mL with deionised water)
- Amount(s) applied: 10 μL
- Concentration: Not specified.

POSITIVE CONTROL
- Name: 5% SLS (Fluka, Sigma-Aldrich) solution in deionised water
- Amount(s) applied: 10 μL
- Concentration (if solution): 5% w/v aqueous solution

Duration of treatment / exposure:

15 minutes

Duration of post-treatment incubation (if applicable):

The tissues were incubated for approximately 41.5 hours at 37 ± 1.5°C, 5 ± 0.5% CO2

Number of replicates:

3 test replicates

Test animals

Species:

other: reconstituted human epidermis model

Strain:

other: reconstituted human epidermis model

Details on test animals or test system and environmental conditions:

Not applicable

Test system

Type of coverage:

other: Topical

Preparation of test site:

other: Not applicable

Vehicle:

other: No vehicle used

Controls:

yes, concurrent positive control

yes, concurrent negative control

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 5 μL of deionised water followed by 10 ± 2 mg of the test item were topically applied to the epidermal surface
- Concentration (if solution): Test material is a solid

VEHICLE
- Not applicable

NEGATIVE CONTROL
- Name: PBS (produced in-house: 40 g NaCl, 1 g KCl, 1 g KH2PO4, 0.94 g Na2HPO4 + 2 H2O filled to 5000 mL with deionised water)
- Amount(s) applied: 10 μL
- Concentration: Not specified.

POSITIVE CONTROL
- Name: 5% SLS (Fluka, Sigma-Aldrich) solution in deionised water
- Amount(s) applied: 10 μL
- Concentration (if solution): 5% w/v aqueous solution

Duration of treatment / exposure:

Treatment: The test item tissues were soaked in 5 μL of deionised water. The controls and test item was added into the insert above the EpiSkin™ triplicate tissues for 15 minutes. The post exposure incubation period was 42 hours.

Observation period:

Not applicable

Number of animals:

Not applicable

Details on study design:

TEST SITE
- Area of exposure: The test material was applied to a human reconstructed epidermis model. The epidermis surface had previously been moistened with 5 μL of distilled water to improve contact between the solid test material and the epidermis.
- % coverage: The test material was applied topically to the corresponding tissues ensuring uniform covering.
- Type of wrap if used: None used

REMOVAL OF TEST SUBSTANCE
- Washing: After the end of the treatment interval the inserts were immediately removed from the 12-well plate. The tissues were gently rinsed with PBS to remove any residual test material. Excess PBS was removed by gently shaking the inserts and blotting the bottom with blotting paper.
- Time after start of exposure: 15 Minutes

SCORING SYSTEM:
- Quantitative MTT Assessment (percentage tissue viability): For the test material, the relative mean tissue viabilities obtained after the 15 minute treatment followed by the 42-hour post-exposure incubation period were compared to the mean of the negative control treated tissues (n=3). The relative mean viabilities were calculated in the following way:
Relative mean tissue viability (percentage of negative control) = (mean OD570 of test material / mean OD570 of negative control) x 100

Classification of irritation potential is based upon relative tissue viability following the 15-minute exposure period followed by the 42-hour post-exposure incubation period according to the following:
Mean tissue viability is ≤50%: Irritant (I) H315 Category 2
Mean tissue viability is >50%: Non-Irritant (NI) Not classified. (Category 3 cannot be determined)

Results and discussion

In vitro

Results

Irritation / corrosion parameter:

% tissue viability

Run / experiment:

Relative mean variability

Value:

96.4

Vehicle controls validity:

not applicable

Negative controls validity:

valid

Positive controls validity:

valid

Remarks on result:

no indication of irritation

Other effects / acceptance of results:

The optical pre-experiment (colour interference pre-experiment) to investigate the test item’s colour change potential in water did not lead to a change in colour.
Optical evaluation of the MTT-reducing capacity of the test item after 3 hour incubation with MTT-reagent did not show blue colour.
The mean relative absorbance value of the test item, corresponding to the cell viability, decreased to 96.4% (threshold for irritancy: ≤ 50%), consequently the test item was not irritant to skin.

Any other information on results incl. tables

Quality Criteria

The acceptance criteria were met:

• the mean OD of the three negative control exposed tissues is ≥ 0.6 till ≤ 1.5 (range: 0.856 to 0.972).

• the rel. standard deviations between tissues of the same treatment group was ≤ 18% (range: 6.6 to 12.7%).

• the mean relative tissue viability of the positive control was ≤ 40% (5.3%).

• the acceptance limit of the IC50 of the respective EpiSkin™ lot was between 1.5 and 3.0 mg/mL after 18 hours treatment with SLS (1.7 mg/mL).

• the results for the positive control are within the historical data (means, rel. standard deviation, and ranges) of Envigo CRS GmbH

• the results for the negative control are within the historical data (means, rel. standard deviation and ranges) of Envigo CRS GmbH (Please note: the study was performed by using PBS, the Historical Control Data Base annexed to the report shows the Data for deionized water; data for PBS are in process and the number of studies is still too low for presenting Historical Data). Comparing the results of PBS to the Historical Control Data Base generated with deionized water is legitimate since both controls are aqueous from the chemical point of view. In other toxicological studies (e.g. OECD 487 or OECD 473) Historical Data Bases distinguish only between aqueous or organic solvents.

RESULTS

The individual and mean absorbance values, standard deviations and tissue viabilities for the test material, negative control material and positive control material are given in Table 1. The relative mean viability of the test material treated tissues was 96.4% after a 15 minutes exposure.

Table 1: Mean absorbance values and percentages for the blank control, negative control material, positive control material and test material.

Results after treatment with test item and controls

Test Group	Absor-bance 570 nm Tissue Well 1	Absor-bance 570 nm Tissue Well 2	Mean Absor-bance 570 nm	Mean Absor-bance 570 nm *	Mean Absor-bance of 3 Tissues	Relative Absor-bance [%] Tissue 1, 2, 3**	Relative Standard Deviation [%]	Rel. Absor-bance [% of Negative Control]***
Blank	0.038	0.038	0.038
Negative Control	0.945	0.905	0.925	0.887	0.880	100.8	6.6	100.0
	0.983	0.960	0.972	0.934		106.2
	0.872	0.840	0.856	0.818		93.0
Positive Control	0.073	0.083	0.078	0.040	0.046	4.5	12.7	5.3
	0.091	0.080	0.086	0.048		5.4
	0.087	0.091	0.089	0.051		5.8
Test Item	0.986	0.961	0.974	0.936	0.848	106.4	9.6	96.4
	0.848	0.890	0.869	0.831		94.5
	0.832	0.794	0.813	0.775		88.1

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test material was considered to be a non-irritant to skin using the EPISKIN™ Reconstructed Human Epidermis Model.

Executive summary:

The study is assigned a reliability score of 1 (reliable without restrictions) as it followed OECD Guideline 439: In vitro Skin Irritation: Reconstructed Human Epidermis Test Method, is compliant with GLP and met the acceptance criteria. The substance, under test conditions, had a mean relative absorbance value, corresponding to cell viability, of 96.4%, which is above the threshold for irritancy (≤50%) and consequently the test item was not irritant to skin.